1. Field of the Invention
The present invention relates to a rotary-head drum device for guiding a magnetic tape in a video tape recorder or the like.
2. Description of the Prior Art
FIG. 1 of the accompanying drawings shows a conventional rotary-head drum device for use in a video tape recorder or the like.
As shown in FIG. 1, a rotary-head drum device, generally denoted at 1, comprises a lower fixed drum 2 fixedly mounted on a base (not shown) and an upper rotatable drum 3 rotatably mounted on the lower fixed drum 2 for high-speed rotation thereon. Circumferentially spaced magnetic heads 4 are attached to the surface of the rotatable drum 3 which confronts the fixed drum 2, the magnetic heads 4 having tip ends projecting radially outwardly from the circumferential surface of the rotatable drum 3.
A lead step 5 is obliquely formed on the circumferential surface of the fixed drum 2. A magnetic tape T is wound around the circumferential surface of the rotary-head drum device 1 with one edge of the magnetic tape T extending along and held against the lead step 5. The magnetic tape T wound around the rotary-head drum device 1 is transported at predetermined speed.
When the rotatable drum 3 rotates at high speed at the same time the magnetic tape T is transported, the magnetic heads 4 slide against and obliquely scan the recording surface of the magnetic tape T for recording or reproducing signals.
The conventional rotary-head drum device 1 does not allow the magnetic heads 4 to contact the magnetic tape T well at an exit point for the magnetic tape T, i.e., a region where the magnetic tape leaves the circumference of the rotary-head drum device 1.
More specifically, while the rotatable drum 3 is rotating, the magnetic heads 4 scan the magnetic tape T while at the same time lifting the magnetic tape T. As shown in FIG. 2, an upper edge of the magnetic tape T is lifted slightly off the circumference of the rotatable drum 3 at the exit point by the magnetic heads 4. At the exit point, therefore, only an edge of the tip end of each of the magnetic heads 4 is held in contact with the recording surface of the magnetic tape T. Particularly, a magnetic tape in the form of a thin-film medium (so-called an ME-type magnetic tape) is not held in good contact with the tip end of the magnetic heads 4 because the magnetic tape is relatively rigid and less flexible, and hence suffers dropouts of recorded and reproduced signals.
Solutions would be to reduce the projection of the magnetic heads 4 from the circumferential surface of the rotatable drum 3 and to adjust or modify the path along which the magnetic tape T travels around the rotary-head drum 1. However, if the projection of the magnetic heads 4 becomes smaller, more dropouts are produced. If the tape path is adjusted or modified, the compatibility ratio is lowered.